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 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.awt.geom;

import java.io.Serializable;

/**
 * The <code>Point2D</code> class defines a point representing a location
 * in {@code (x,y)} coordinate space.
 * <p>
 * This class is only the abstract superclass for all objects that
 * store a 2D coordinate.
 * The actual storage representation of the coordinates is left to
 * the subclass.
 *
 * @author Jim Graham
 * @since 1.2
 */
public abstract class Point2D implements Cloneable {

  /**
   * The <code>Float</code> class defines a point specified in float
   * precision.
   *
   * @since 1.2
   */
  public static class Float extends Point2D implements Serializable {

    /**
     * The X coordinate of this <code>Point2D</code>.
     *
     * @serial
     * @since 1.2
     */
    public float x;

    /**
     * The Y coordinate of this <code>Point2D</code>.
     *
     * @serial
     * @since 1.2
     */
    public float y;

    /**
     * Constructs and initializes a <code>Point2D</code> with
     * coordinates (0,&nbsp;0).
     *
     * @since 1.2
     */
    public Float() {
    }

    /**
     * Constructs and initializes a <code>Point2D</code> with
     * the specified coordinates.
     *
     * @param x the X coordinate of the newly constructed <code>Point2D</code>
     * @param y the Y coordinate of the newly constructed <code>Point2D</code>
     * @since 1.2
     */
    public Float(float x, float y) {
      this.x = x;
      this.y = y;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public double getX() {
      return (double) x;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public double getY() {
      return (double) y;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public void setLocation(double x, double y) {
      this.x = (float) x;
      this.y = (float) y;
    }

    /**
     * Sets the location of this <code>Point2D</code> to the
     * specified <code>float</code> coordinates.
     *
     * @param x the new X coordinate of this {@code Point2D}
     * @param y the new Y coordinate of this {@code Point2D}
     * @since 1.2
     */
    public void setLocation(float x, float y) {
      this.x = x;
      this.y = y;
    }

    /**
     * Returns a <code>String</code> that represents the value
     * of this <code>Point2D</code>.
     *
     * @return a string representation of this <code>Point2D</code>.
     * @since 1.2
     */
    public String toString() {
      return "Point2D.Float[" + x + ", " + y + "]";
    }

    /*
     * JDK 1.6 serialVersionUID
     */
    private static final long serialVersionUID = -2870572449815403710L;
  }

  /**
   * The <code>Double</code> class defines a point specified in
   * <code>double</code> precision.
   *
   * @since 1.2
   */
  public static class Double extends Point2D implements Serializable {

    /**
     * The X coordinate of this <code>Point2D</code>.
     *
     * @serial
     * @since 1.2
     */
    public double x;

    /**
     * The Y coordinate of this <code>Point2D</code>.
     *
     * @serial
     * @since 1.2
     */
    public double y;

    /**
     * Constructs and initializes a <code>Point2D</code> with
     * coordinates (0,&nbsp;0).
     *
     * @since 1.2
     */
    public Double() {
    }

    /**
     * Constructs and initializes a <code>Point2D</code> with the
     * specified coordinates.
     *
     * @param x the X coordinate of the newly constructed <code>Point2D</code>
     * @param y the Y coordinate of the newly constructed <code>Point2D</code>
     * @since 1.2
     */
    public Double(double x, double y) {
      this.x = x;
      this.y = y;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public double getX() {
      return x;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public double getY() {
      return y;
    }

    /**
     * {@inheritDoc}
     *
     * @since 1.2
     */
    public void setLocation(double x, double y) {
      this.x = x;
      this.y = y;
    }

    /**
     * Returns a <code>String</code> that represents the value
     * of this <code>Point2D</code>.
     *
     * @return a string representation of this <code>Point2D</code>.
     * @since 1.2
     */
    public String toString() {
      return "Point2D.Double[" + x + ", " + y + "]";
    }

    /*
     * JDK 1.6 serialVersionUID
     */
    private static final long serialVersionUID = 6150783262733311327L;
  }

  /**
   * This is an abstract class that cannot be instantiated directly.
   * Type-specific implementation subclasses are available for
   * instantiation and provide a number of formats for storing
   * the information necessary to satisfy the various accessor
   * methods below.
   *
   * @see java.awt.geom.Point2D.Float
   * @see java.awt.geom.Point2D.Double
   * @see java.awt.Point
   * @since 1.2
   */
  protected Point2D() {
  }

  /**
   * Returns the X coordinate of this <code>Point2D</code> in
   * <code>double</code> precision.
   *
   * @return the X coordinate of this <code>Point2D</code>.
   * @since 1.2
   */
  public abstract double getX();

  /**
   * Returns the Y coordinate of this <code>Point2D</code> in
   * <code>double</code> precision.
   *
   * @return the Y coordinate of this <code>Point2D</code>.
   * @since 1.2
   */
  public abstract double getY();

  /**
   * Sets the location of this <code>Point2D</code> to the
   * specified <code>double</code> coordinates.
   *
   * @param x the new X coordinate of this {@code Point2D}
   * @param y the new Y coordinate of this {@code Point2D}
   * @since 1.2
   */
  public abstract void setLocation(double x, double y);

  /**
   * Sets the location of this <code>Point2D</code> to the same
   * coordinates as the specified <code>Point2D</code> object.
   *
   * @param p the specified <code>Point2D</code> to which to set this <code>Point2D</code>
   * @since 1.2
   */
  public void setLocation(Point2D p) {
    setLocation(p.getX(), p.getY());
  }

  /**
   * Returns the square of the distance between two points.
   *
   * @param x1 the X coordinate of the first specified point
   * @param y1 the Y coordinate of the first specified point
   * @param x2 the X coordinate of the second specified point
   * @param y2 the Y coordinate of the second specified point
   * @return the square of the distance between the two sets of specified coordinates.
   * @since 1.2
   */
  public static double distanceSq(double x1, double y1,
      double x2, double y2) {
    x1 -= x2;
    y1 -= y2;
    return (x1 * x1 + y1 * y1);
  }

  /**
   * Returns the distance between two points.
   *
   * @param x1 the X coordinate of the first specified point
   * @param y1 the Y coordinate of the first specified point
   * @param x2 the X coordinate of the second specified point
   * @param y2 the Y coordinate of the second specified point
   * @return the distance between the two sets of specified coordinates.
   * @since 1.2
   */
  public static double distance(double x1, double y1,
      double x2, double y2) {
    x1 -= x2;
    y1 -= y2;
    return Math.sqrt(x1 * x1 + y1 * y1);
  }

  /**
   * Returns the square of the distance from this
   * <code>Point2D</code> to a specified point.
   *
   * @param px the X coordinate of the specified point to be measured against this
   * <code>Point2D</code>
   * @param py the Y coordinate of the specified point to be measured against this
   * <code>Point2D</code>
   * @return the square of the distance between this <code>Point2D</code> and the specified point.
   * @since 1.2
   */
  public double distanceSq(double px, double py) {
    px -= getX();
    py -= getY();
    return (px * px + py * py);
  }

  /**
   * Returns the square of the distance from this
   * <code>Point2D</code> to a specified <code>Point2D</code>.
   *
   * @param pt the specified point to be measured against this <code>Point2D</code>
   * @return the square of the distance between this <code>Point2D</code> to a specified
   * <code>Point2D</code>.
   * @since 1.2
   */
  public double distanceSq(Point2D pt) {
    double px = pt.getX() - this.getX();
    double py = pt.getY() - this.getY();
    return (px * px + py * py);
  }

  /**
   * Returns the distance from this <code>Point2D</code> to
   * a specified point.
   *
   * @param px the X coordinate of the specified point to be measured against this
   * <code>Point2D</code>
   * @param py the Y coordinate of the specified point to be measured against this
   * <code>Point2D</code>
   * @return the distance between this <code>Point2D</code> and a specified point.
   * @since 1.2
   */
  public double distance(double px, double py) {
    px -= getX();
    py -= getY();
    return Math.sqrt(px * px + py * py);
  }

  /**
   * Returns the distance from this <code>Point2D</code> to a
   * specified <code>Point2D</code>.
   *
   * @param pt the specified point to be measured against this <code>Point2D</code>
   * @return the distance between this <code>Point2D</code> and the specified <code>Point2D</code>.
   * @since 1.2
   */
  public double distance(Point2D pt) {
    double px = pt.getX() - this.getX();
    double py = pt.getY() - this.getY();
    return Math.sqrt(px * px + py * py);
  }

  /**
   * Creates a new object of the same class and with the
   * same contents as this object.
   *
   * @return a clone of this instance.
   * @throws OutOfMemoryError if there is not enough memory.
   * @see java.lang.Cloneable
   * @since 1.2
   */
  public Object clone() {
    try {
      return super.clone();
    } catch (CloneNotSupportedException e) {
      // this shouldn't happen, since we are Cloneable
      throw new InternalError(e);
    }
  }

  /**
   * Returns the hashcode for this <code>Point2D</code>.
   *
   * @return a hash code for this <code>Point2D</code>.
   */
  public int hashCode() {
    long bits = java.lang.Double.doubleToLongBits(getX());
    bits ^= java.lang.Double.doubleToLongBits(getY()) * 31;
    return (((int) bits) ^ ((int) (bits >> 32)));
  }

  /**
   * Determines whether or not two points are equal. Two instances of
   * <code>Point2D</code> are equal if the values of their
   * <code>x</code> and <code>y</code> member fields, representing
   * their position in the coordinate space, are the same.
   *
   * @param obj an object to be compared with this <code>Point2D</code>
   * @return <code>true</code> if the object to be compared is an instance of <code>Point2D</code>
   * and has the same values; <code>false</code> otherwise.
   * @since 1.2
   */
  public boolean equals(Object obj) {
    if (obj instanceof Point2D) {
      Point2D p2d = (Point2D) obj;
      return (getX() == p2d.getX()) && (getY() == p2d.getY());
    }
    return super.equals(obj);
  }
}
